Study links women's fashion sense to ovulation

Women are more likely to dress to impress when they are at their most fertile, according to psychologists. A study of female university students found they eschewed drab clothing for a more flamboyant style when they were ovulating, suggesting hormonal changes had an unconscious effect on their behaviour.

Photographs of the women revealed they more frequently wore jewellery as well as trendy and more revealing clothes at the most fertile phase of their monthly cycle. "They tend to put on skirts instead of pants, show more skin and generally dress more fashionably," said Martie Haselton, the University of California Los Angeles researcher who led the study.

Dr Haselton said some women appeared to make subtle tweaks to their usual dress when they were most fertile, such as donning more striking tops and adding necklaces and earrings. The women were not necessarily dressing more provocatively.

"We did see a little bit more skin. It was my impression that women were just dressing a little bit more fashionably, but not sexier," she said.

The psychologists recruited 30 female university students and staff aged 18 to 37 and invited them to attend the lab as part of the study, but did not explain to them what the experiment was investigating. The women visited the lab several times a month and gave urine samples which were tested for female hormones to calculate the 15th day of their menstrual cycle, the day of ovulation.

The women were photographed twice, once within a few days of their most fertile phase and again in their least fertile phase. Dr Haselton's group then blacked out the faces in the photographs and asked a mixed panel of 17 men and 25 women to say in which photo each woman was trying to look more attractive.

The judges picked the photos of women at their most fertile an average of 60% of the time, according to the journal Hormones and Behaviour. Those women photographed on the exact day of ovulation were picked 83% of the time.

"This is well beyond chance. They were pretty consistent," Dr Haselton said.

Writing in the journal, the psychologists claim their findings disprove the conventional wisdom that women are unique among animals in concealing, even from themselves, when they are most fertile.

In the animal kingdom, displays of fertility abound. Some female crabs secrete powerful sex pheromones into the water to attract males, while female elephants, which may be fertile for less than a week every five years, let out a low-pitched bellow to attract nearby males. But overt signs of human ovulation have proved notoriously difficult to detect.

"We're not saying women evolved to dress more sexily when they are most fertile, but we believe evolution has shaped their motivations and behaviours," said Dr Haselton.

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